SiliconPlatformPort.__len__ was broken after recent changes, fix

Author: robtaylor

chipflow_lib/platforms/silicon.py

@@ -131,7 +131,6 @@ def __len__(self):
         if self._direction is io.Direction.Input:
             return len(self._i)
         if self._direction is io.Direction.Output:
-            assert len(self._o) == len(self._oe)
             return len(self._o)
         if self._direction is io.Direction.Bidir:
             assert len(self._i) == len(self._o)